Abstract
In this study, we explored the adaptive mechanism of two varieties of Angelica sinensis exposed to enhanced Ultraviolet-B (UV-B) radiation. The radiation had different effects on the biomass, photosynthetic performance, oxidative damage, antioxidant defense system, and levels of bioactive compounds of Mingui 1 (C1) and Mingui 2 (C2). C2 outperformed C1 under enhanced UV-B radiation, compared to natural light. Using the Illumina RNA-seq, we obtained 6,326 and 2,583 DEGs in C1 and C2, respectively. Under enhanced UV-B radiation, the mRNA levels of genes involved in photosynthesis, antennae protein synthesis, carbon fixation, chlorophyll synthesis, and carotenoid synthesis were decreased in C1 but stable in C2, involving few DEGs. TFs were widely involved in the response of C1 to enhanced UV-B radiation; almost all bHLH and MYB coding genes were downregulated whereas almost all genes encoded WRKY22, WRKY50, WRKY72, NCF, and HSF were upregulated. These results indicate that enhanced UV-B radiation was not conducive to the synthesis of flavonoids, while disease resistance was enhanced. Regarding the ROS scavenging system, upregulated DEGs were mainly found in the AsA-GSH cycle and PrxR/Trx pathways. Remarkably, DEGs that those encoding biosynthetic key enzymes, including ferulic acid (CHS, CHI, DFR, and ANS) and flavonoid (CHS, CHI, DFR, and ANS), most upregulation in C2, leading to increased accumulation of ferulic acid and flavonoids and adversely affecting C1. Genes encoding key enzymes involved in the synthesis of lactone components (ACX, PXG) were mostly up-regulated in C1, increasing the content of lactone components. Our results reveal the DEGs present between C1 and C2 under enhanced UV-B radiation and are consistent with the observed differences in physiological and biochemical indexes. C1 was more sensitive to enhanced UV-B radiation, and C2 was more tolerant to it under moderate enhanced UV-B radiation stress. In addition, the large amount of A. sinensis transcriptome data generated here will serve as a source for finding effective ways to mitigate UV-B enhancement, and also contribute to the well-established lack of genetic information for non-model plant species.
Highlights
Radix Angelica Sinensis (RAS) is the dried root of Angelica sinensis (Oliv.) Diels, which has been used as both a medicine and for nourishment in the form of spice and tonic for more than 1,000 years in China, South Korea, and Japan
The number of differentially expressed gene (DEG) was lower in C2 than in compounds of Mingui 1 (C1). These results indicate that the activities of antioxidant enzymes in leaves increased under enhanced UV-B radiation, which maintained the ability of plants to scavenge reactive oxygen species (ROS) and prevented damage to leaves, preserving photosynthetic efficiency
photosynthetic rate (Pn), levels of photosynthetic pigments (Chl a, Chl b, and Car), antioxidant enzyme activities (SOD, POD, and CAT), and accumulation of bioactive substances were maintained or were enhanced in C2, and MDA accumulation was stable under enhanced UV-B radiation
Summary
Radix Angelica Sinensis (RAS) is the dried root of Angelica sinensis (Oliv.) Diels, which has been used as both a medicine and for nourishment in the form of spice and tonic for more than 1,000 years in China, South Korea, and Japan. Today, it is still one of the most commonly used herbs by practitioners of Traditional Chinese Medicine (TCM) in China as well as Europe (Wei et al, 2016). More than 70 active compounds have been identified in RAS, including polysaccharides, ferulic acid, coniferyl ferulate, Z-ligustilide, E3-butylidenephthalide, and other phthalides (Hook, 2014). In the past 10 years, due to global climate warming, and severe early bolting and root diseases, the planting area of A. sinensis has gradually changed from low-altitude mountain valleys to high-altitude slopes; it is being exposed to enhanced UV-B stress (An et al, 2020)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
